In recent years, a head-mounted image display device of a so-called see-through type has come into practical use. It allows a user to view an image of an image-display element while viewing the outside (disclosed in Patent Document 1).
An image display device described in Patent Document 1 uses a polarization beam splitter (hereinafter, referred to as a “PBS”) as a combiner which reflects the polarizing light flux from an image-display element, so that it reduces a loss of light intensity. To obtain this advantageous effect, the posture of the PBS of the image display device is inclined relative at 45° to an optical path. Accordingly, the posture of the PBS is also inclined at 45° relative to a surface of a substrate.
Patent Document 1: U.S. Pat. No. 5,886,822